Turned on SkSL->GLSL compiler

src/sksl/ast/SkSLASTPrecision.h

+/*
+ * Copyright 2016 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+ 
+#ifndef SKSL_ASTPRECISION
+#define SKSL_ASTPRECISION
+
+#include "SkSLASTDeclaration.h"
+#include "../ir/SkSLModifiers.h"
+
+namespace SkSL {
+
+/**
+ * Represents a precision declaration (e.g. 'precision mediump float;').
+ */
+struct ASTPrecision : public ASTDeclaration {
+    // FIXME handle the type
+    ASTPrecision(Position position, Modifiers::Flag precision)
+    : INHERITED(position, kPrecision_Kind)
+    , fPrecision(precision) {}
+
+    std::string description() const {
+        switch (fPrecision) {
+            case Modifiers::kLowp_Flag: return "precision lowp float;";
+            case Modifiers::kMediump_Flag: return "precision mediump float;";
+            case Modifiers::kHighp_Flag: return "precision highp float;";
+            default: 
+                ASSERT(false); 
+                return "<error>";
+        }
+        ASSERT(false);
+        return "<error>";
+    }
+
+    const Modifiers::Flag fPrecision;
+
+    typedef ASTDeclaration INHERITED;
+};
+
+} // namespace
+
+#endif